scanrep: reliability of 3d lower limb scanning

Conditions: Foot Injuries and Disorders

Summary: 3d limb scanning systems have recently been implemented for the clinical fitting of prosthetic and orthotic devices due to substantial decreases in costs. however, little data is available regarding the repeatability and validity of systems currently in use. in this study the investigators seek to evaluate the repeatability and validity of multiple lower limb measurements obtained using low-cost 3d limb scanning technology.

two groups of subjects will be recruited for this study. the first group (group 1) will consist of healthy able-bodied individuals with no history of lower extremity trauma. the second group (group 2) will consist of individuals with unilateral, below knee functional deficits that require an afo (ankle foot orthosis) for daily activities (e.g. fracture, muscle and/or nerve injury, ankle arthritis, or peripheral neurologic disease). the investigators will obtain a brief medical history to identify major medical conditions or prior injuries that could influence limb geometry, and lead to reliance on an afo for group 2 participants. a 3d representation of each participant's lower limb geometry will be obtained using a structure core scanner (occipital, inc.) which uses an infrared structured light projector to construct a 3d image of an object. the scanner is connected to an ipad; to operate the user rotates the ipad camera around the desired object. in seconds, the entire geometry is digitally reconstructed. measurements will be evaluated using digital imaging analysis software (standard cyborg, inc.). the investigators will evaluate concurrent validity by directly comparing software-based measurements from limb scans, with direct measurements on the same individual collected using digital calipers. the investigators will determine repeatability of each technique by conducting three identical limb scans and actual physical measurements at two time points on the same day in each individual, and then comparing the results between time points. the interior of the afo worn by participants in group 2 will also be scanned to obtain its geometry for comparison with measurements obtained from each individual's limb. validity and repeatability will be assessed using measurements at multiple locations on the lower leg. limb measurements will include 1) width of the metatarsal heads, 2) width of the calcaneus, 3) foot length, 4) foot height, 5) arch height, 6) medial-lateral width between ankle malleoli, 7) minimum circumference above the ankle malleoli, 8) maximum calf circumference , 9) medial-lateral width of the knee condyles 10) anterior-posterior width at mid patellar tendon, 11) distance from bottom of foot to tibial tubercle. concurrent validity will be determined using the intra-class correlation coefficient and absolute error (root mean square error) for comparisons between measurements from limb scanning and the calipers. reliability will be determined using the intra-class correlation coefficient and the minimal detectable change value for comparisons over time.

Eligibility criteria:
group 1 patient inclusion criteria * ages: 18-75 * healthy individuals without a current complaint of lower extremity pain, spine pain, active infections or medical or neuromusculoskeletal disorders that have limited participation in work or exercise in the last 6 months * ability to perform a full squat without pain * able to read and write in english and provide written informed consent patient exclusion criteria * diagnosed moderate or severe brain injury * diagnosis of a physical or psychological condition that would preclude testing (e.g. cardiac condition, clotting disorder, pulmonary condition) * current complaint of pain or numbness in the spine * uncorrected visual or hearing impairments that limit the ability to understand or comply with instructions given during testing * require an assistive device * open/unhealed wounds on lower extremity. * bmi greater than 35 group 2 patient inclusion criteria * ages: 18-75 * daily afo use to address unilateral below knee functional deficits (e.g. fracture, muscle and/or nerve injury, ankle arthritis, or peripheral neurologic disease) * ability to stand independently without use of an assistive device (cane, crutch, etc) * ability to safely bear full body weight on affected limb without use of an afo or other protection * able to read and write in english and provide written informed consent patient exclusion criteria * use of an afo that crosses the knee (includes knee brace or similar) * open/unhealed wounds on lower extremity * uncorrected visual or hearing impairments that limit the ability to understand or comply with instructions given during testing * bmi greater than 35 * diagnoses of a moderate to severe brain injury

Keywords: ankle foot orthosis adult 3d limb scanning limb geometry